/**
 * Returns whether SIXEL passthrough is explicitly enabled.
 *
 * Both gates must be enabled to preserve SIXEL control sequences:
 * - PI_FORCE_IMAGE_PROTOCOL=sixel
 * - PI_ALLOW_SIXEL_PASSTHROUGH=1
 */
export declare function isSixelPassthroughEnabled(): boolean;
/** Returns true when the text contains a SIXEL start sequence. */
export declare function containsSixelSequence(text: string): boolean;
/**
 * Returns a boolean mask indicating which lines belong to a SIXEL sequence block.
 * Supports multi-line SIXEL payloads generated by libsixel.
 */
export declare function getSixelLineMask(lines: string[]): boolean[];
/** Returns true when the line contains a SIXEL start sequence. */
export declare function isSixelLine(line: string): boolean;
/**
 * Sanitizes text while preserving embedded SIXEL sequences when passthrough is enabled.
 */
export declare function sanitizeWithOptionalSixelPassthrough(text: string, sanitize: (text: string) => string): string;